It always create a nother file
The Blend1 files are your previous manual saves. This is so that if something goes catastrophically wrong with the most recent file (and that you can't fix it), you can load up previous manual saves (Blend1 files).

If you wish to disable this:

Go to Edit > User Preferences
Then go to the "Save &amp; Load" tab.
Reduce the number of "Save Versions" to 0.